DWDM Mux/Demux using 40G Optics

Mon Jun 19 18:43:03 UTC 2017

The guys at fibrestore will point you in the right direction on all this if you ask them these questions. They are actually very helpful and will assign you a specialist to assist.

-------- Original message --------
From: Colton Conor <colton.conor at gmail.com> 
Date: 20/06/17  6:26 AM  (GMT+12:00) 
To: NANOG <nanog at nanog.org> 
Subject: DWDM Mux/Demux using 40G Optics 

We are building a 40G metro ring using 40-Gigabit Ethernet QSFP+
Transceivers. Specifically, we are using Juniper JNP-QSFP-40G-LR4. This is
a QSFP+ Transceiver with a LC duplex head. We only have one pair of single
mode dark fibers around the ring.  Our distance between nodes around the
ring are all less than 10KM, so we can use standard optics.

We go out of one JNP-QSFP-40G-LR4 and into another JNP-QSFP-40G-LR4. There
are no passive muxes involved. This is working great for 40G.

My understanding is a JNP-QSFP-40G-LR4 is really a transceiver with a CWDM
mux built into it. The spec sheet shows it sends 4 10G channels:

https://www.juniper.net/documentation/en_US/release-independent/junos/topics/reference/specifications/optical-interface-qfx-support.html

Lane wavelength
Lane 0–1264.5 nm through 1277.5 nm
Lane 1–1284.5 nm through 1297.5 nm
Lane 2–1304.5 nm through 1317.5 nm
Lane 3–1324.5 nm through 1337.5  nm

This setup is working fine, but now we want to do more than 40G around the
ring. To my knowledge there are no other 40G QSFP+ transceivers that use
four other channel/lanes than the ones already being used, so they only way
to go higher than 40G is to stack 10G or 100G channels ontop of the fiber
pair using a passive mux.

100G is too expensive for the time being, so we are looking to add 10G
channels to a ring that already have one 40G channel using the QSFP+.

I was reading this tutorial, and it mentions "there is a 1310 nm port
integrated in a 40 channels DWDM Mux/Demux system. The 1310nm added port is
a Wide Band Optic port (WBO) added to other specific DWDM wavelengths in a
module. When we run out of all channels in a DWDM Mux/Demux system, we can
add the extra optics via this 1310nm port."
http://www.fs.com/upgrade-to-500g-with-40ch-dwdm-mux-demux-system-aid-493.html

What I can't seem to understand is they are mentioning that this 1310 port
can pass QSFP+ signals, so it sounds like its really a 1270nm through
1330nm port? Is this what they mean by   Wide Band Optic port (WBO)?

We don't need 40 10G channels plus a 40G for a total of 440G. More than
likely we are looking at a 8 channel mux/demux, and 1 40G port for a total
of 120G.

I don't care if we do CWDM vs DWDM, but I assume it will be hard to find a
CWDM mux that has one LC dupluex input for  1270nm through 1330nm channels?

Maybe I should just ditch the 40G QSFP+ optics and use all 10G optics, but
the switches I am using have 48 10G SFP+ ports and 6 QSFP+ ports built in.
I know there are 40G breakout cables, but the whole point of 40G is to
aggregate VLAN/circuits.

Has anyone done this before?